Abstract
Background: Lateral ankle sprains (LAS) are a common injury. Many individuals do not seek care after injury and may develop chronic ankle instability (CAI). Individuals with CAI have decreased dorsiflexion range of motion (ROM), ankle eversion strength, and postural control. In addition, those with CAI have been shown to have a more inverted foot position during walking gait compared to healthy controls. Copers are individuals who have had an ankle sprain but learn to cope and return to pre-injury levels of function and may be a better comparison group than healthy controls because they have had the same initial injury. Previously, impairment-based rehabilitation has shown to improve strength, balance, and range of motion (ROM) in individuals with CAI, however, ankle inversion during walking gait remained unchanged. Gait training focused on decreasing ankle inversion may be an appropriate technique to address the altered gait mechanics in those with CAI with hopes to reduce the risk of recurrent ankle sprains.
Purpose: The purpose of Manuscript 1 (M1) was to simultaneously analyze lower extremity walking gait kinematics, kinetics, and surface electromyography (sEMG) between individuals with CAI and copers at a preferred walking speed (PWS), 120% preferred walking speed (120WS), and standardized walking speed (SWS) of 1.34 m/s. The primary purpose for Manuscript 2 (M2) was to analyze the effects of 4-weeks of visual gait biofeedback and impairment-based rehabilitation on gait biomechanics and patient-reported outcomes (PRO) in individuals with CAI. Clinical outcome measures of strength, balance, and ROM were assessed for the biofeedback and no biofeedback groups in Manuscript 3 (M3).
Methods: M1) A case-control study of 36 physically active individuals (Copers: n=18, CAI: n=18) was performed to assess group differences for kinematics in sagittal, frontal, and transverse planes of the ankle, knee, and hip during walking at 3 walking speeds. M2 & M3) We performed a single-blinded randomized controlled trial to analyze the effects of 4-weeks of impairment-based rehabilitation and visual gait biofeedback compared to a no biofeedback. M2) Lower extremity walking gait biomechanics and PROs were assessed at baseline and follow-up time points. M3) Range of Motion (ROM), balance, and strength were assessed at baseline and follow-up time points.
Results: M1) The CAI group had more ankle inversion at IC (PWS: CAI=3.3+3.4º, Coper=-1.1+4.6º; 120WS: CAI=3.6+3.7º, Coper =-1.4+4.1º; SWS: CAI=4.4+4.6, Coper=-2.2+5.0º) and throughout swing at all three walking speeds (Peak inversion: PWS: CAI=5.6+5.1º, Coper=0.4+4.3º; 120WS: CAI=5.6+5.4º, Coper=1.2+4.2º; SWS: CAI=6.8+5.9º, Coper=0.6+4.2º). CAI had greater peak hip adduction during swing (PWS: CAI=-5.1+5.7º, Coper=-0.6+3.4º; 120WS: CAI = -5.1+4.5º, Coper=-1.0+3.3º; SWS: CAI=-5.2+4.2º, Coper=-1.6+3.1º). M2) The biofeedback group significantly decreased ankle inversion at IC (pre:4.24.6º, post:-3.14.1º, g=1.6) and throughout the entire stride cycle (peak inversion: pre:6.75.0º, post:0.84.3º, g=1.2). The no biofeedback group did not have any significant changes in gait biomechanics. The groups were significantly different after rehabilitation while accounting for baseline measures for FAAM-ADL (biofeedback:97.12.3%, no biofeedback:92.05.7%), TSK (biofeedback:29.73.7, no biofeedback:34.95.8), and GROC (biofeedback:5.51.0, no biofeedback:3.92.0) with the biofeedback group showing greater improvements than the no biofeedback group. M3) The biofeedback group significantly increased in plantarflexion ROM (pre: 74.1 6.9º, post: 82.27.4º) compared to the no biofeedback group (pre: 72.37.8º, post: 72.310.0º). Greater strength improvements (N/kg) were found in the biofeedback group for ankle inversion (biofeedback: pre: 2.30.6, post: 3.40.7; no biofeedback: pre: 2.60.4, post 3.10.5), 1st toe flexion (biofeedback: pre: 1.10.3, post: 2.10.3; no biofeedback: pre: 1.20.3, post 1.80.4), and hip abduction (biofeedback: pre: 1.90.5, post: 2.70.5; no biofeedback: 2.30.5, 2.50.5) compared to the no biofeedback group. There were no significant differences between the groups for balance measures.
Conclusion: Ankle inversion in the CAI group got larger and lasted for more of the gait cycle as the speed increased which may put them at greater risk for recurrent sprains. The coper group used a strategy that resulted in a more everted foot position and abducted hip position which may reduce the risk of injury. Gait training for CAI individuals should be modeled after copers’ gait mechanics. In our second study, the biofeedback group successfully decreased ankle inversion angle and had greater improvements in PRO’s after the intervention. The biofeedback group adopted a kinematic pattern at the ankle that more closely represented that of the copers in our first study. Impairment-based rehabilitation without biofeedback improved PRO’s but did not impact gait biomechanics. Additionally, impairment-based rehabilitation in combination with visual biofeedback resulted in greater improvements in strength and ROM compared to the no biofeedback group. This combination of visual biofeedback and impairment-based rehabilitation is recommended for individuals with CAI.
